Hi guys, I just finished switching my original 37 amp alternator on my '67with external regulator to a 12SI alternator. I did a search and bypassed the regulator by soldering the blue and brown wires at the old regulator and capped off the old white and red ones. At the alternator, I wired the new plug like this: white wire on the new plug (#1) to the exsisting blue wire, and the red wire (#2) to the alternator output stud. Now comes the problem. I have 14.2 volts at the battery when running (down to 13.8 with all accesories, including my new electric fan on), but the generator light in the dash is glowing slightly. I did a voltage drop test on the positive side of the charging system (0.2-0.3V), so that looks ok. The voltage at the alternator stud is same as battery voltage, why is the generator light glowing??

I've got the same set up in my el camino, and its doing the same thing, hopefully someone can give us a answer. JIm

Hi there, go to MAD enterprises and they have a diagram on how to do the alternator conversion. There is a diagram on what to do with the wires. I would go to that site just to double check your work. I belive that your gen lite problem has something to do with your alternator conversion...

With the engine off and the key on, unplug the alternator connector. See if the light goes off. It should.

Engine off, key on, unplugged alternator plug and light went off. Plugged it back in and started car, light stayed on bright for a couple of seconds, went out completely, back on again for a couple seconds, now is back to glowing again. Also noticed the stud for the main charging wire at the back of the alternator can be wiggled slightly, is this normal? I'm aware of MAD's wiring instructions, but have also been told by several sources that the way I wired it up is all I need to do. I figured with 14.1 volts at the battery, I was charging good.

Sounds like it's wired correctly and the alternator is controlling the light. Think I would have the alternator checked out at the auto parts store.

Thanks for the advice guys,

The generator light problem is fixed :)
The fact that the output stud on the back of the alternator was loose was bothering me, so I pulled the alternator, took it apart and tightened the nut by the rectifier, and no more problems. :)